entity_as_of

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full burden. It accurately describes the return value (entity or null) and the validity logic. It implies a read-only query, but does not explicitly state that it is non-destructive or free of side effects. Lacks some explicit behavioral traits.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three sentences, each earning its place: high-level purpose, return behavior, and detailed validity condition. Front-loaded with the key concept 'time-travel query'. No wasted words.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Adequate for a simple query tool with two well-documented parameters, but lacks information about the output shape (what fields the returned entity has) and error handling (e.g., if entity does not exist). Without output schema, some context is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema already fully describes parameters (name and asOf) with 100% coverage. The description adds value by explaining how asOf is used in the validity formula (validFrom <= asOf AND (validUntil undefined OR validUntil >= asOf)), which goes beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool performs a 'time-travel query for an entity' and returns it at a given point in time. It specifies the resource (entity) and action (query by asOf). However, it does not explicitly distinguish from sibling tools like get_entity_versions or entity_timeline, so it misses a 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage when you need an entity's state at a specific date and provides the validity condition, but it does not give explicit guidance on when to use this tool versus alternatives, nor does it mention when not to use it.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.